Exhaust gas treatment device frequently operate with ceramic substrate bodies, for example, catalytic converters and particle filters. Depending on the purification task, the substrate bodies in catalytic converters may have a catalytically active coating in order to form an oxidation catalytic converter or a DeNox catalytic converter or a three-way catalytic converter or a hydrolytic catalytic converter or an ammonia-blocking catalytic converter. The substrate bodies are usually manufactured from a piece consisting of a uniform material, i.e., monolithically, so that they form a monolith each. Depending on the purification task, flow is also possible through two or more ceramic substrate bodies. Furthermore, it may be possible, to increase efficiency, to arrange two or more substrate bodies one after another. Two or more substrate bodies, which differ from one another, for example, by different pore sizes, may also be arranged one after another in a particle filter. Substrate bodies having different purification tasks, i.e., especially with different catalytic coatings, may also be arranged in a common housing.
To achieve a compact design, such an exhaust gas treatment device may have a tubular housing, in which either exactly one ceramic substrate body is arranged for exhaust gas treatment, or at least two ceramic substrate bodies are arranged one after another for the exhaust gas treatment. Such ceramic substrate bodies are usually mounted in a metallic housing by means of mounting mats. The mounting mats are compressed radially in this case. The insertion of the substrate bodies with mounting mat into the housing is usually called “canning.” Axial canning, in which the respective substrate body is inserted with the mounting mat axially into the tubular housing, is of interest here.
To secure the axial position of the substrate body within the housing, it is possible, in principle, to provide an axial support at the housing, at which support the respective substrate body can be axially supported. Such an axial support is preferably arranged on the outlet side or discharge side of the respective substrate body. If at least two substrate bodies are arranged one after another in the housing in an exhaust gas treatment device, it is desirable to support the substrate body arranged upstream at the housing by means of such an axial support in order to prevent an axial displacement of the substrate through which the exhaust gas flows first, because such displacement may lead to a collision with the substrate body arranged downstream and thus to a risk of damage to both substrates. This makes it difficult to mount or manufacture the exhaust gas treatment device. For example, the substrate body located upstream must be inserted into the housing from the inlet side of the housing in a housing that contains such an axial support, while the substrate body located downstream must be inserted into the housing through an outlet side of said housing in order for the axial support to be subsequently arranged axially between the two substrate bodies. Depending on the canning method, the housing must be turned in a corresponding canning device for this. An axial support is likewise desirable for protection from a collision of the substrate body with the housing in an exhaust gas treatment device that contains only a single substrate body, in connection with which similar problems arise during manufacture.